Insulin consists of two short polypeptide chains: chain A and chain B, that are linked together by

Options

A. hydrogen bonds
B. disulphide bridges
C. DNA ligase
D. DNA polymerase

Answer

**Step-by-Step Solution:**

1. **Understanding Insulin Structure**: Insulin is a protein that consists of two short polypeptide chains, known as chain A and chain B.

2. **Identifying the Chains**: Chain A and chain B are synthesized separately. In the context of biotechnology, these chains are often produced using genetically modified bacteria, such as E. coli.

3. **Linking the Chains**: After the two chains are synthesized, they need to be linked together to form the functional insulin molecule.

4. **Chemical Bonds Involved**: The chains are linked by specific types of chemical bonds. The options given in the question include hydrogen bonds, disulfide bridges, DNA ligase, and DNA polymerase.

5. **Eliminating Incorrect Options**:
- Hydrogen bonds are not strong enough to hold the structure of insulin together.
- DNA ligase and DNA polymerase are enzymes involved in DNA replication and repair, not in linking polypeptide chains.

6. **Correct Answer**: The two polypeptide chains, chain A and chain B, are linked together by **disulfide bridges** (also known as disulfide bonds). This is the correct answer to the question.

---